Sulfur quantum dot based fluorescence assay for lactate dehydrogenase activity detection

Lactate dehydrogenase (LDH) plays an important role in the process of glycolysis as well as gluconeogenesis, and is related to many diseases, so it is of great significance to accurately detect LDH activity in serum. The fluorescence of sulfur quantum dots (SQDs) synthesized by the microwave method can be specifically enhanced by nicotinamide adenine dinucleotide (NAD + ). Based on this characteristic, we reported a sensitive fluorescence assay for LDH detection. In the presence of reductive coenzyme I (NADH), LDH catalyzes the reduction of pyruvate to lactic acid, and transforms NADH to NAD + , which specifically enhances the fluorescence intensity of SQDs. Based on the fluorescence intensity increase, the assay achieved detection of LDH in the range from 500 to 40,000 U L −1 , with limit of detection of 262 U L −1 . The assay was successfully applied for the detection of LDH activity in serum, indicating potential clinical applications.